In November 2001, the National Security Agency began illegally intercepting Americans’ phone calls and emails without warrants or suspicion of wrongdoing. In 2008, Congress amended the Foreign Intelligence Surveillance Act (FISA), rubber-stamping this warrantless wiretapping program and giving the NSA power to conduct dragnet surveillance of Americans’ international communications.

Despite the post-9/11 warrantless wiretapping of Americans, the NSA says that citizens should trust it not to abuse its growing power and that it takes the Constitution and the nation’s privacy laws seriously.

But one of the agency’s biggest secrets is just how careless it is with that ocean of very private and very personal communications, much of it to and from Americans. Increasingly, obscure and questionable contractors — not government employees — install the taps, run the agency’s eavesdropping infrastructure, and do the listening and analysis.

And with some of the key companies building the U.S.’s surveillance infrastructure for the digital age employing unstable employees, crooked executives, and having troubling ties to foreign intelligence services, it’s not clear that Americans should trust the secretive agency, even if its current agency chief claims he doesn’t approve of extrajudicial spying on Americans...